1. Field of the Invention
The present invention relates to a light source, or more particularly, to an optical axis adjustment mechanism for moving a lamp house to adjust an optical axis of illumination light a source lamp emits.
2. Description of the Related Art
In a light source for supplying light to a fiberscope, an optical axis of illumination light to be emitted is adjusted so that light will be supplied in an optimal state to an intended region (back end surface of a light guide for a fiberscope). Specifically, the optical axis of illumination light to be emitted is adjusted to coincide with the intended region, so that the illumination light will be emitted toward the intended region. In general, an art of moving a lamp house and an art of moving an optical block made up of condensers, a diaphragm adjustment mechanism for adjusting an amount of light, and a light guide receptor for a fiberscope are known for adjusting an optical axis of illumination light.
For instance, an art based on a feed screw mechanism has been proposed as the art of moving a lamp house in Japanese Utility Model Unexamined Publication No. 57-110815.
To be more specific, as shown in FIG. 1, a feed screw mechanism 2 made up of a feeder 2a, a coupling 2b for moving the feeder 2a vertically, and a gear 2c for turning the coupling 2b, is placed below a lamp house 1. The gear 2c of the feed screw mechanism 2 is manipulated from vertically to rotate. Thereby, the feeder 2a is moved vertically via the coupling 2b. Then, the lamp house 1 is moved to adjust a optical axis vertically.
When an optical axis is moved vertically or horizontally and thus adjusted, a lamp house should, preferably, be moved while being held horizontal so that the optical axis will not be displaced in a direction other than the moving direction and varied its orientation. However, according to the aforesaid prior art of moving a lamp house, when a feed screw is used, a backlash of the screw causes the lamp house to waver and makes it hard to move the lamp house vertically while keeping it horizontal. Then, use of a large-diameter feed screw is conceived to cope with this problem. However, use of a large-diameter feed screw generally causes parts to become unusable, thereby increasing cost.
When the lamp house is moved vertically to adjust the optical axis, the feed screw mechanism placed below the lamp house must be vertically manipulated. Therefore, the housing of the light source must be uncovered to adjust the optical axis.
On the other hand, according to an art of moving an optical block to adjust an optical axis, as shown in FIGS. 2 and 3, a base member 6 joined with the bottom of an optical block 5 is screwed to a base 8 having a guide axis 7 via springs 9. The screws 10 are loosened to move the base member 6 vertically. Thereby, the optical block 5 is adjusted vertically and secured at an appropriate position by tightening the screws 10.
Even when the optical block is moved to adjust the optical axis, the optical block should preferably be moved while being kept horizontal so that the orientation of the optical axis will not vary. However, according to the foregoing art of moving the optical block to adjust the optical axis, the center of gravity of the optical block and the center of the base member joined with the bottom of the optical block do not lie on the same vertical axis. Therefore, the base member rubs against the contact surfaces on the right and left of the base and the guide axis, causing a jerk. This makes it hard to move the optical block vertically and smoothly while keeping it horizontal.